1. Field of the Invention
The present invention relates generally to computer input devices, and in particular, to a method and apparatus for the wireless capture of coordinate-shift information.
2. Background Art
Among computer input devices, mice and/or cursor pens are commonly used together with many computer systems. Conventional mice and cursor pens are generally coupled to the computer system by a cable or other wire for the transfer of information therebetween. However, such cabled or wires connections can be cumbersome in use. As a result, wireless mice and cursor pens were introduced to overcome this problem, and have become very popular in the marketplace.
In general, the conventional wireless mice and cursor pens require the use of a battery set as a power source. However, the sizes of a conventional computer mouse and pen are small, so that the installation of a battery set inside the housing of these devices can be burdensome to the weight, size and use of these devices. In addition, battery-operated wireless mice and cursor pens can provide erroneous signals when the battery becomes weak.
Moreover, conventional wireless mice and cursor pens usually utilize frequency modulation techniques to transmit the resonance signals. However, the use of frequency modulation techniques suffers from certain drawbacks. For example, frequency modulation techniques require circuits that have increased complexity, and often lead to unstable frequency responses and other inaccuracies.
Thus, there remains a need for a wireless input device and system that overcomes the disadvantages set forth above, which avoids the use of a battery set, and which is effective in detecting the coordinate-shift information within a specified working area.
It is an object of the present invention to provide a method and apparatus for the wireless capture of coordinate-shift information in a manner which can accurately detect the movement or shifting of the input device in a specified working area.
It is another object of the present invention to provide a method and apparatus for the wireless capture of coordinate-shift information in which batteries are not needed to power the input device.
It is yet another object of the present invention to provide a method and apparatus for the wireless capture of coordinate-shift information which provides optimal efficiency in push-button signal processing.
The objects of the present invention can be accomplished by providing a method for the wireless capture of coordinate shift information using movement of a position indicator within a working area. The method includes generating a signal; simultaneously distributing the signal along a first path that includes the working area, and a second path; detecting the times at which the signals from the first and second paths arrive at a common location; and determining the coordinate shift information based on the difference between the arrival times of the signals from the first and second paths.
The present invention can be implemented by an apparatus that includes a pulse generator that generates a pulse signal and simultaneously distributes the pulse signal into a first signal along the first path and a second signal along the second path. The apparatus further includes a working area defined by a plurality of crossing X-axis signal lines and Y-axis signal lines, and at least one coil surrounding the working area for generating a magnetic field. The apparatus also includes a scanning circuit coupled to the working area, and a synchronic determination circuit coupled to the pulse generator and the scanning circuit for receiving the first and second signals, and for determining the time delay between the receipt of the first and second signals. The apparatus further includes a signal processing circuit coupled to the scanning circuit and the synchronic determination circuit. The first signal passes through the working area and the scanning circuit to the synchronic determination circuit, and contains coordinate shift information.
According to one embodiment of the present invention, the position indicator can include a resonance circuit that receives signals from the magnetic field, and then re-transmits resonance signals having different pulse widths to the working area. The position indicator also includes a pulsewidth control circuit coupled to the resonance circuit for changing the width of the resonance signals, and a push-button circuit coupled to the pulsewidth control circuit and the resonance circuit.